An IC is a device (e.g., a semiconductor device) or electronic system that includes many electronic components, such as transistors, resistors, diodes, etc. These components are often interconnected to form multiple circuit components, such as gates, cells, memory units, arithmetic units, controllers, decoders, etc. An IC includes multiple layers of wiring that interconnect its electronic and circuit components.
Design engineers design ICs by transforming logical or circuit descriptions of the ICs' components into geometric descriptions, called design layouts. IC design layouts typically include circuit modules (e.g., geometric representations of electronic or circuit IC components) with pins, and interconnect lines (e.g., geometric representations of wiring) that connect the pins of the circuit modules. A net is typically defined as a collection of pins that need to be connected. In this fashion, design layouts often describe the behavioral, architectural, functional, and structural attributes of the IC. To create the design layouts, design engineers typically use electronic design automation (“EDA”) applications. These applications provide sets of computer-based tools for creating, editing, analyzing, and verifying design layouts.
Large IC designs are often designed by design engineers using a hierarchical design methodology, in which cells are pre-designed and pre-characterized. A standard cell is a group of transistor and interconnect structures that provides a boolean logic function (e.g., AND, OR, XOR, XNOR, inverters) or a storage function (flipflop or latch). However, higher level cells may be complete microprocessors or memory arrays. The cells are then placed and interconnected within the design of the IC or of higher level cells. The cells may be designed for reuse many times in many different ICs, or may be designed for a single use before their exact placement and surrounding cells and wires are known. Therefore, it is desirable to avoid any restrictions in their layout or characterization that would restrict the locations in which they may be placed or the patterning of shapes in the cells and wires that may surround them.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.